Glassy State and Cryopreservation of Mint Shoot Tips

Vitrification refers to the physical process by which a liquid supercools to very low temperatures and finally solidifies into a metastable glass, without undergoing crystallization at a practical cooling rate. Thus, vitrification is an effective freeze‐avoidance mechanism and living tissue cryopreservation is, in most cases, relying on it. As a glass is exceedingly viscous and stops all chemical reactions that require molecular diffusion, its formation leads to metabolic inactivity and stability over time. To investigate glassy state in cryopreserved plant material, mint shoot tips were submitted to the different stages of a frequently used cryopreservation protocol (droplet‐vitrification) and evaluated for water content reduction and sucrose content, as determined by ion chromatography, frozen water fraction and glass transitions occurrence by differential scanning calorimetry, and investigated by low‐temperature scanning electron microscopy, as a way to ascertain if their cellular content was vitrified. Results show how tissues at intermediate treatment steps develop ice crystals during liquid nitrogen cooling, while specimens whose treatment was completed become vitrified, with no evidence of ice formation. The agreement between calorimetric and microscopic observations was perfect. Besides finding a higher sucrose concentration in tissues at the more advanced protocol steps, this level was also higher in plants precultured at 25/?1°C than in plants cultivated at 25°C. © 2013 American Institute of Chemical Engineers Biotechnol. Prog., 29:707–717, 2013     

Development of Asparagus plumosus Shoot Tips Grown in vitro

Lateral shoot tips from young Asparagus setaceus (Kunth) Jessop (syn. A. plumosus Baker) shoots were grown on a modified Murashige and Skoog medium. Tips from 5 to 20 mm lateral shoots had significantly better growth and development than tips from lateral shoots (2 mm) still covered by leaf-scale. The optimum temperature for growth and development of the explants was 17 to 24°C. The initial growth was fast at 24°C but stopped after about 4 weeks. At 17°C the growth was slow but in return the cultures continued to grow. Kinetin was necessary for growth. Without any kinetin all cultures died. Optimum growth was found with 2 mg/l kinetin. There was no growth at all with IAA alone. A low IAA concentration had no effect, but at high concentrations IAA inhibited the kinetin induced growth.     

园艺植物茎尖冷冻疗法脱毒的技术研究

超低温冷冻疗法是超低温保存技术在植物脱毒上的一个新的应用。由于其脱毒率高,操作简单,被认为是最有效脱除植物病毒的方法,为脱毒苗的生产开辟了一条新的途径。本文就超低温冷冻疗法脱毒的原理、操作程序、关键技术和在园艺植物上的最新研究进展进行综述,并对其今后的发展进行了展望。     

Genetic Identification of Hyalodaphnia Species and Interspecific Hybrids

Species of the genus Daphnia, in particular the subgenus Hyalodaphnia, represent a taxonomically problematic group due to their phenotypic plasticity, local races and the formation of interspecific hybrids and backcrosses. In this study, we present a genetic approach utilising nuclear DNA to unequivocally identify species and interspecific hybrids. Several nuclear loci (ITS1-ITS2, CA14 and GA13) were amplified by PCR and products were subjected to diagnostic restriction enzymes (restriction fragment length polymorphism; RFLP). The application of this approach to several populations across Europe revealed that the markers are highly consistent and reproducible. In addition, we illustrate with a number of examples how this approach contributed to unravel previously unrecognised taxa, increased the sensitivity of biodiversity studies or contributed to the analysis of resting egg banks. Advantages and disadvantages of this approach compared to existing techniques are discussed and several empirical studies and their results are summarised.     

Influence of Cytokinins and Temperature on Development of Asparagus plumosus Shoot Tips in vitro

Lateral shoot tips from young shoots of Asparagus setaceus (Kunth) Jessop (syn. A. plumosus Baker) were grown on a modified Murashige and Skoog medium. PBA was the most effective cytokinin for growth and development of Asparagus plumosus shoot tips. The optimal range of PBA was between 0.02 and 2 mg/1. Zeatin was less effective, and kinetin, BA and 2iP were poor as cytokinins for A. plumosus. The optimal temperature for growth and development was 21°C. There was interaction between the temperature and the PBA concentration. With increasing temperature from 17 to 24°C the need for PBA increased from 0.2 to 2 mg/1.     

Developmental Capacity of Aneuploid Xenopus Species Hybrids

Diploid as well as triploid Xenopus interspecific hybrids generate aneuploid eggs because of the presence, at meiosis, of univalent chromosomes which are presumably distributed at random. Zygotes obtained from such eggs, fertilized by either normal or UV-irradiated sperm, were analysed for their developmental capacities. All monosomics die in the course of embryogenesis, whereby optimum capacities correspond closely with those observed in monosomic mammalian embryos, especially in mice. In contrast, hyperdiploid Xenopus are relatively viable: although many die exhibiting the'haploid syndrome'or various other abnormalities, 8% of them reach metamorphosis, and 1–2% become adults. Of the latter, the karyotype was established in 13 individuals. Among them, 8–16 supernumerary chromosomes were found to be present.     

喜树幼枝的喜树碱积累及其组织内定位

对喜树幼枝发育过程中各组织结构变化的观察和喜树碱含量的分析,以及荧光显微技术对喜树碱的定位研究,结果表明,幼茎和幼叶表面的单细胞腺毛和幼茎及幼叶内部由1～2层细胞包围而成的分泌道是喜树碱的主要积累部位.     

Proteomic Analysis of Shoot Tips from Two Alfalfa Cultivars with Different Florescence

Plant Molecular Biology Reporter - Flowering is an indispensable biological process for the complete life cycle of angiosperms, crucial to the regeneration of plants and the continuation of...     

Shoot Anatomy of Three Bulbous Species of Oxalis

The shoots of Oxalis latifolia, O. corymbosa and O. oxypteraare comprised of underground bulbs which send out stolons withapical and lateral bulbs. The external scales of the bulbs formthe base of the leaves; an adnation of the stipules to the petioleoccurs as well. In O. oxyptera the bulb shows primitive charactersand can be considered a rhizome-shaped bulb. Incipient secondarygrowth and schizo-lysigenous secretory cavities are described.An ascending evolutionary sequence of O. oxyptera, O. latifoliaand O. corymbosa is proposed based on the vegetative system. Oxalis spp., Oxalidaceae, shoot anatomy, bulb, stolons     

红花石蒜茎尖的玻璃化超低温保存

2～3mm的石蒜茎尖放在MS+0.4mol·L-1蔗糖的培养基上预培养5d,在25℃下用预处理液处理20min,接着用冰浴的玻璃化保护剂PVS2在冰浴中处理80min后,换新鲜PVS2并迅速投入液氮。液氮保存24h后,于40℃水浴中快速解冻2min,用MS+1.2mol·L-1蔗糖的液体培养基洗涤20min,滤纸吸干后接种到恢复培养基中,在25℃下暗培养7d后,转入光照强度为36μmol·m-2·s-1和光暗周期12/12h条件下培养。2周后的成活率最高可达90%,植株再生率达53%。     

In Vitro Multiplication of Beta Vulgaris L. throughout Excised Shoot Tips

Friable calli were induced from mature excised shoots of Bambusa vulgaris on Murashige and Skoog's (MS) medium supplemented with 2.2 μM6-benzylamino-purine (BAP), 9.04 μM 2,4-dichlorophenoxyacetic acid and 14.76 μM indole-3-butyric acid (IBA) with 3 % (m/v) saccharose. Adventitious shoots with root hairs were achieved from calli on MS medium supplemented with 13.33 μM BAP and 1.23 - 2.46 μM IBA within 4 weeks of subculture. The frequency of shoot bud regeneration was better in the light incubated cultures than in the dark incubated cultures. Isolated shoots were rooted on liquid half-strength MS basal medium supplemented with 0.49 μM IBA and 2 % (m/v) saccharose. Histological observations confirmed the regeneration of shoot buds from calli. The rooted plantlets were successfully transferred to greenhouse. This revised version was published online in July 2006 with corrections to the Cover Date.     

Preparative Procedures and Culture Medium Affect the Success of Cryostorage of Holostemma annulare Shoot Tips

Shoot tip cryopreservation of Holostemma annulare, an endangered medicinal plant was carried out using Murashige-Skoog (MS) medium containing mM NH⁺ ₄+NO^– ₃; 20.6+39.4 (MS-1), 2.6+18.8 (MS-2) or 0.0+18.8 (MS-3). The three media combinations were tested during four preparative procedures viz.: development of cultures; preconditioning of shoot tip cuttings; preculture of encapsulated shoot tips; and post-freeze recovery to understand the most critical phase of NH₄NO₃ sensitivity. MS-1 used during the initial three preparative steps supported 10.9–16.6% post-freeze recovery of cryopreserved shoot tips. Development of culture in MS-1 and subsequent passages (2nd, 3rd and 4th preparative steps) in MS-2 or MS-3 improved the recovery rate to 26.4–35.8%. MS-3 used throughout the steps favoured 38.5% recovery. Shoot tips from shoot cultures raised in MS-2 upon preconditioning in MS-2 or MS-3 and subsequent preculture of encapsulated shoot tips and post-freeze recovery culture in MS-3 showed maximum regeneration (55%). MS-2 used throughout the procedure supported 48% regeneration of cryopreserved shoot tips.     

Abscisic Acid in Prunus Trees: Isolation and the Effect on Growth of Excised Shoot Tissue

The abscisic acid content of the mature shoot tissue of vigorous Prunus avium, medium sized Prunus cerasus and dwarfing Prunus cerasus self (S) was estimated by spectropolarimetry and gas chromatography. There is no correlation between the levels of ABA found in the tissue and the dwarfing potential of the trees investigated. However, Prunus arium stem tissue shows the lowest sensitivity to ABA, whereas the explants of normal and dwarfing Prunus cerasus exhibit a stronger inhibition.     

Cryopreservation of Shoot Tips of Tetraploid Potato (Solanum tuberosumL.) Clones by Vitrification

In vitro-grown shoot tips of five tetraploid potato (SolanumtuberosumL.) clones were cryopreserved by vitrification. Excisedshoot tips (0.5–0.7 mm) were pre-cultured on filter paperdiscs over half strength liquid Murashige and Skoog (MS) mediumsupplemented with 8.7 µMGA₃and different combinationsof sucrose (0.3, 0.5 and 0.7M) plus mannitol (0, 0.2 and 0.4M)for 2 d under a 16 h photoperiod at 24 °C. The pre-culturedshoot tips were either successively loaded with 20 and 60% PVS2 solutions or directly exposed to concentrated vitrificationsolution before physical vitrification during liquid nitrogentreatment. The vitrified shoot tips were warmed rapidly andtreated with dilution mixture (MS+1.2Msucrose) for 30 min beforeplating on regrowth medium. Addition of mannitol to the pre-culturemedium improved survival of vitrified shoot tips. Direct dehydrationof pre-cultured shoot tips with concentrated PVS 2 was detrimentalto survival of vitrified shoot tips. Shoot tips pre-culturedon medium containing 0.3Msucrose plus 0.2Mmannitol, and loadedwith 20% PVS 2 for 30 min followed by 15 min incubation in 60%PVS 2 and 5 min incubation in 100% PVS 2 at 0 °C resultedin up to 54% survival after vitrification. About 50% of vitrifiedand warmed shoot tips formed shoots directly. Post-thaw culturingof vitrified shoot tips on medium containing an elevated levelof sucrose (0.2M) under diffuse light for the first week enhancedthe survival rate. Continuous culturing of vitrified shoot tipson high-sucrose medium induced multiple shoot formation.Copyright1998 Annals of Botany Company Solanum tuberosumL., potato, cryopreservation, germplasm conservation,in vitroconservation, meristems, shoot tips, tissue culture, vitrification.     

Histochemical Localization of {beta}-Glycerophosphatase Activity in Young Root Tips

Glycerophosphatase activity has been studied in frozen sectionsof maize, barley, and broad-bean root tips by the Gomori leadsulphide precipitation procedure. The enzyme was largely localizedat particulate sites in the cytoplasm, and in the cell walls.In maize and barley the particles were similar to acid phosphatase-containingspherosomes found in other tissues and were most active in thecortical cells. The wall reaction was highest in the outer cells,in agreement with biochemical studies. When excised roots wereincubated in the Gomori medium, staining was restricted to thesurface cells. The possible function of this surface activityand its relevance to ultrastructural studies is discussed.